U.S. patent application number 11/834933 was filed with the patent office on 2008-04-03 for rotating electrical machine and alternating-current generator.
This patent application is currently assigned to Hitachi, Ltd.. Invention is credited to Hiroshi KANAZAWA, Masashi Kitamura, Takayuki Koyama, Susumu Tajima, Kenya Takarai.
Application Number | 20080079322 11/834933 |
Document ID | / |
Family ID | 38460613 |
Filed Date | 2008-04-03 |
United States Patent
Application |
20080079322 |
Kind Code |
A1 |
KANAZAWA; Hiroshi ; et
al. |
April 3, 2008 |
Rotating Electrical Machine And Alternating-Current Generator
Abstract
It is made easy for a stator winding to be wound around a stator
core and degradation in efficiency is prevented as much as
possible. A stator 6 includes a plurality of phases, i.e., of
circumferentially divided stator magnetic poles 6a, 6b, 6c. The
stator magnetic poles 6a, 6b, 6c are each composed of an arcuate
stator core 13 having a plurality of axially extending claw poles
16b and a circumferentially elliptically wound stator winding 14.
The stator magnetic poles 6a, 6b, 6c are magnetically divided;
therefore, magnetic flux leakage is reduced to improve efficiency.
Air flowing between the stator magnetic poles 6a, 6b, 6c can
improve a cooling effect.
Inventors: |
KANAZAWA; Hiroshi;
(Hitachiohta, JP) ; Koyama; Takayuki; (Hitachi,
JP) ; Kitamura; Masashi; (Mito, JP) ; Tajima;
Susumu; (Hitachinaka, JP) ; Takarai; Kenya;
(Atsugi, JP) |
Correspondence
Address: |
CROWELL & MORING LLP;INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Assignee: |
Hitachi, Ltd.
Tokyo
JP
|
Family ID: |
38460613 |
Appl. No.: |
11/834933 |
Filed: |
August 7, 2007 |
Current U.S.
Class: |
310/44 ; 310/198;
310/257; 310/263; 310/54; 310/58 |
Current CPC
Class: |
H02K 19/22 20130101;
H02K 1/243 20130101; H02K 5/128 20130101; H02K 1/145 20130101; H02K
1/148 20130101 |
Class at
Publication: |
310/44 ; 310/198;
310/216; 310/257; 310/54; 310/58 |
International
Class: |
H02K 1/12 20060101
H02K001/12; H02K 3/04 20060101 H02K003/04; H02K 9/00 20060101
H02K009/00; H02K 9/02 20060101 H02K009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2006 |
JP |
2006-263722 |
Claims
1. A rotating electric machine comprising: a stator; and a rotor;
wherein said stator includes a plurality of stator windings
circumferentially arranged at predetermined intervals and a stator
core, said stator core includes a stator yoke and a plurality of
claw poles extending from said stator yoke, passing through an
inside opening and an outside of said stator core and protruding
toward the side of said rotor, and said stator yoke is magnetically
divided in association with said stator winding.
2. The rotating electric machine according to claim 1, wherein said
stator core is divided into a pair of segments each located from
the inside opening of said stator winding to a corresponding one of
both the axial sides thereof.
3. The rotating electric machine according to claim 1, wherein said
stator core is axially divided at a position of said stator
winding.
4. The rotating electric machine according to claim 1, wherein said
stator core is axially divided into four stator core constituent
members at the inside opening of said stator winding and at the
position of said stator winding, said stator core constituent
members being formed to have the same shape.
5. The rotating electric machine according to claim 1, wherein said
stator core is composed of a dust core.
6. The rotating electric machine according to claim 1, wherein at
least one circumferential end portion of said stator winding
protrudes from said stator core.
7. The rotating electric machine according to claim 6, wherein an
odd number of said claw poles are provided for each magnetically
divided stator yoke.
8. The rotating electric machine according to claim 6, wherein an
even number of said claw poles are provided for each magnetically
divided stator yoke.
9. The rotating electric machine according to claim 1, wherein said
rotor is disposed on the inner circumferential side of said stator
core and drives a pump, a partition wall made of a nonmagnetic
material is disposed between said claw poles and said rotor, and a
discharge medium to be discharged by the pump is led into the
inside of a partition wall including said rotor.
10. The rotating electric machine according to claim 9, wherein the
discharge medium is a cooling medium.
11. The rotating electric machine according to claim 1, wherein
said stator winding is wound to be exposed from said stator core on
an axial end side of said stator core.
12. The rotating electric machine according to claim 11, wherein
said stator cores are opposed to each other for forming a pair on
the side where said stator winding is not exposed.
13. The rotating electric machine according to claim 1, wherein
said claw pole is tapered.
14. A rotating electric machine comprising: a stator; and a rotor;
wherein said stator includes a plurality of stator windings
circumferentially arranged at predetermined intervals and a stator
core, said stator core is configured to be provided along a
circumferential portion of said stator winding and to form a
plurality of magnetic poles on the side of said rotor, and said
stator core is divided for each of said stator windings.
15. The rotating electric machine according to claim 14, wherein a
positioning member for positioning said stator core is fitted to an
axial end face of each of the divided stator cores.
16. The rotating electric machine according to claim 15, wherein
said stator core is axially divided into a plurality of stator core
constituent members with respect to the inside opening of said
stator winding, said stator core constituent members having the
same shape, and a connecting member made of a magnetic material is
fitted to said stator core constituent members at a position
corresponding to the inside opening of said stator winding and
where said stator core constituent members are opposed to each
other.
17. An alternating-current generator comprising: a stator; and a
rotor; wherein said stator includes a plurality of stator windings
circumferentially arranged at predetermined intervals and a stator
core, said stator core includes a stator yoke and a plurality of
claw poles extending from said stator yoke, passing through an
inside opening and outside of said stator core and protruding
toward the side of said rotor, said stator yoke is magnetically
divided in association with said stator winding, and a magnetic
flux generated by said rotor passes through said claw poles and is
interlinked with said stator winding, and the magnetic flux
interlinked with said stator winding varies based on rotation of
said rotor to induce voltage in said stator winding.
18. The alternating-current generator according to claim 17,
wherein an air passage adapted to axially pass air therethrough is
provided between said stator windings and ventilating means for
allowing air to flow through the air passage is provided.
19. The alternating-current generator according to claim 18,
wherein said rotor is disposed on the inner circumferential side of
said stator core, and the ventilation means is composed of a fan
which is mounted at least one axial end side of said rotor and
which has an external diameter greater than that of said rotor.
20. The alternating-current generator according to claim 17,
wherein the magnetically divided stator core includes a pair of
said claw poles, said stator core windings are each wound around a
corresponding one of said claw poles and said claw poles are
configured to have a phase-difference in electric angle
therebetween.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a rotating electrical
machine and an alternating-current generator each of which is
provided with a plurality of stator windings.
[0003] 2. Description of the Related Art
[0004] General stators used for rotating electrical machines are
configured to include a stator core formed with a plurality of
slots extending in a circumferential direction and a plurality of
stator windings each of which is wound around a corresponding one
of the slots. This poses a problem in that if the number of slots
formed on the stator core is increased in order to ensure the
number of magnetic poles, work for winding the stator windings in
the slots is complicated to degrade workability.
[0005] To eliminate such a problem, as disclosed in
JP-A-2005-532775, a stator is conceived in which a plurality of
stator windings are each wound circumferentially and a plurality of
claw poles are each formed to pass the inside opening and outside
of each stator winding. With such a configuration, workability
encountered when the stator winding is wound can be improved while
ensuring the number of magnetic poles.
SUMMARY OF THE INVENTION
[0006] In JP-A-2005-532775, since a stator core is integrally
formed in a circumferential direction, however, magnetic flux
generated around the stator winding tends to leak to another stator
winding side, which degrades efficiency.
[0007] It is an object of the present invention to provide a
rotating electrical machine and an alternating-current generator
that make it possible for a stator winding to be wound on a stator
core and prevent degradation in efficiency as much as possible.
[0008] According to an aspect of the present invention, there is
provide a rotating electric machine in which a stator includes a
plurality of stator windings circumferentially arranged at
predetermined intervals and a stator core including a stator yoke
and a plurality of claw poles extending from the stator yoke,
passing through an inside opening and an outside of the stator core
and protruding toward the side of the rotor, the stator yoke being
magnetically divided in association with the stator winding.
[0009] According to another aspect of the present invention, there
is provided a rotating electric machine in which a stator includes
a plurality of stator windings circumferentially arranged at
predetermined intervals and a stator core configured to be provided
along a circumferential portion of the stator winding and to form a
plurality of magnetic poles on the side of the rotor, the stator
core being divided for each of the stator windings.
[0010] According to another aspect of the present invention, there
is provide an alternating-current machine in which a stator
includes a plurality of stator windings circumferentially arranged
at predetermined intervals and a stator core including a stator
yoke and a plurality of claw poles extending from the stator yoke,
passing through an inside opening and outside of the stator core
and protruding toward the side of the rotor, the stator yoke being
magnetically divided in association with the stator winding, and a
magnetic flux generated by the rotor passes through the claw poles
to be interlinked with the stator winding, the magnetic flux
interlinked with the stator winding varying based on rotation of
the rotor to induce voltage in the stator winding.
[0011] The rotating electric machine and alternating-current
generator of the present invention reduce magnetic flux leakage to
improve efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an external view of an electric water pump
according to a first embodiment.
[0013] FIG. 2 is a front cross-sectional view of a motor portion of
the electric water pump of FIG. 1.
[0014] FIG. 3 is an enlarged view of a U-phase portion of FIG.
2.
[0015] FIG. 4 is a perspective view of separate component parts
included in a W-phase portion of a disassembled stator in the first
embodiment.
[0016] FIG. 5 is a perspective view of separate component parts of
an electric motor portion of the second embodiment.
[0017] FIG. 6 is a lateral cross-sectional view of a vehicle
alternating-current generator according to a third embodiment.
[0018] FIG. 7 is a perspective view of a rotor and a stator in the
vehicle alternating-current generator of FIG. 6.
[0019] FIG. 8 is a perspective view of the rotor and stator of FIG.
7 with the stator spaced apart toward the outer circumference and
with a fan secured to the rotor removed.
[0020] FIG. 9 is an enlarged perspective view of a W-phase magnetic
pole in the stator according to a third embodiment.
[0021] FIG. 10 is a perspective view of a stator and a rotor
according to a fourth embodiment.
[0022] FIG. 11A is a perspective view of a stator and a rotor
according to a fifth embodiment.
[0023] FIG. 11B is a perspective view illustrating only a V-phase
magnetic pole and a W-phase magnetic pole according to the fifth
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0024] A description will be made of a first embodiment of a
product using a rotating electric machine embodying the present
invention, taking an electric water pump mounted on an automobile
with reference to FIGS. 1 to 4. FIG. 1 is an external appearance
view of an electric water pump. FIG. 2 is a front cross-sectional
view of a motor portion of the electric water pump. FIG. 3 is an
enlarged view of a U-phase portion of FIG. 2. FIG. 4 is a
perspective view of separate component parts included in a W-phase
portion of a disassembled stator.
[0025] The electric water pump 1 shown in FIG. 1 is used to cool an
electric motor for drive, an inverter, the inside of a cabin, an
internal combustion engine, etc. used in hybrid vehicles, electric
vehicles or the like and serves to deliver to a heat generation
source cooling water as a cooling medium cooled by a radiator.
[0026] The electric water pump 1 is such that an electric motor as
a rotating electric machine and a pump construct are accommodated
in a housing 2, and a pump is rotatably activated by the electric
motor to discharge cooling water. This housing 2 includes an
almost-bowl-like front bracket 2a, a cylindrical housing main body
2b and a plate-like rear plate 2c, which are joined together with
fixation screws 3. Such component parts are molded with an aluminum
material as a nonmagnetic material.
[0027] The front bracket 2a accommodates the pump construct therein
and includes a water supply port 4 provided at a radially
almost-central position and a water discharge port 5 provided on
the outer circumferential side to be opened in an almost-tangential
direction. Incidentally, the pump construct not shown adopts a
centrifugal pump in which an impeller is rotatably driven by the
electric motor to discharge the cooling water led from the water
supply port 4 by a centrifugal force, from the discharge port 5.
The cooling water is not mere water but antifreeze liquid
containing ethylene glycol used as cooling water for
automobiles.
[0028] The housing main body 2b accommodates the electric motor
therein and the impeller of the pump construct is attached to the
output portion of the electric motor. One end opening of the
housing main body 2b is sealed by the rear plate 2c.
[0029] An electrical motor portion as the rotating electrical
machine is next described. Referring to FIG. 2, the electric motor
portion is configured to include a stator 6 secured to the inner
circumference of the housing main body 2b and a rotor 7 provided on
the inner circumference of the stator 6 rotatably with respect to
the stator 6.
[0030] A shaft 8 is disposed at the central portion of the rotor 7.
The rotor 7 is constructed slidably with respect to the shaft 8 via
a sliding bearing 9 provided around the shaft 8. A yoke 10
constituting a magnetic circuit is provided on the outer
circumference of the sliding bearing 9 and a permanent magnet 11 is
provided on the outer circumferential portion of the yoke 10. In
FIG. 2, the number of the magnetic poles of the permanent magnet 11
is 20 poles and magnetic poles, N-poles and S-poles, are
alternately arranged on the circumference. For the rotor 7, the
sliding bearing 9, yoke 10 and permanent magnet 11 can be
fabricated by axially stacking copper powder, magnetic powder and
magnet powder, respectively, and by compacting them by a press. An
impeller (not shown) is secured to the axial end face of the rotor
7. The impeller (not shown) is rotated along with the rotation of
the rotor 7, whereby the pump construct discharges cooling water.
Further, a partition wall 12 made of a nonmagnetic material such as
aluminum, resin or the like is provided on the outer
circumferential portion of the rotor 7 so as to prevent the entry
of the cooling water into the stator side.
[0031] The stator 6 is next described. The stator 6 is disposed on
the inner circumferential side of the housing main body 2b
mentioned above so as to be divided into a U-phase magnetic pole
6a, a V-phase magnetic pole 6b and a W-phase magnetic pole 6c.
Since the stator 6 of the present invention is designed to have
three phases, the number of the stators 6 is three and the stators
6 are arranged at about 120 degrees intervals in view of the
balance of mechanical arrangement. More specifically, to have a
phase difference of three phases, the stator magnetic poles 6a, 6b,
6c of the phases are arranged to have the phase differences of 120
and 240 degrees with the electric angles of the permanent magnet 11
provided on the rotor 7. Since such phases are not mechanically
connected to each other, the stator magnetic poles 6a, 6b, 6c are
fixedly supported at their inner and outer circumferences by the
partition wall 12 and housing main body 2b, respectively, mentioned
above.
[0032] Further, a description is made of a detailed structure of
the stator magnetic poles 6a, 6b, 6c of the stator 6 taking a
W-phase magnetic pole shown in FIG. 4 as an example. Each of the
stator magnetic poles 6a, 6b, 6c of the stator 6 is composed of a
stator core 13 and a stator winding 14 wound in the stator core
13.
[0033] The stator core 13 is composed of a pair of axially divided
stator sub-cores 15 and each of the stator sub-cores 15 is composed
of a pair of axially divided stator core constituent members 16. In
short, the stator core 13 is composed of four stator core
constituent members 16, which have the same shape. The stator core
constituent member 16 is made of a dust core whose surface is
coated with an insulating member, the dust core being hardened by
compacting iron powder. One of the stator core constituent members
16 is formed by integrally molding a stator yoke 16a and three claw
poles 16b. The stator yoke 16a has an arcuately formed strip-like
portion 16a-1 and a key groove portion 16a-2 provided to protrude
toward the inner circumferential side from one axial end of the
strip-like portion 16a-1. The claw pole 16b axially extends from
the key groove portion 16a-2 of the stator yoke 16a. The three claw
poles 16b are each formed to be tapered, that is, to be almost
trapezoidal and are spaced apart at almost equal intervals from a
circumferential end of the key groove portion 16a-2. Thus, the claw
pole 16b is not arranged on the other side of the key groove
portion 16a-2. The claw poles 16b of the two stator core
constituent members 16 configured described above are axially
assembled with each other so as to be alternately arranged, thereby
forming the stator sub-core 15. Further, the two stator sub-cores
15 are axially assembled with each other so as to be symmetrical,
thereby forming the stator core 13. In this case, the opposed claw
poles 16b of the stator core constituent members 16 are brought
into contact with each other to contribute to an increase in
mechanical strength and to increase a coefficient of use of
magnetic flux, thereby providing an effect of increased output.
Incidentally, the stator cores 15 are joined together in a state
where an arcuate connecting member 17 made of a magnetic body is
fitted into the key grooves 16a-3 formed on the surfaces of the
stator yokes where the pair of stator sub-cores 15 are opposed to
each other.
[0034] The stator winding 14 is internally wound around the stator
core 13 constructed as above. The stator winding 14 is molded by
deforming a cylindrically wound winding into an ellipse and by
further circumferentially bending it into a saddle. The stator
winding 14 is flat wound to be radially narrow and axially wide and
includes a pair of coil end portions 14a formed at both
circumferential ends and a pair of circumferentially wound portions
14b present between both the coil end portions 14a. The stator core
constituent members 16 are assembled around the stator winding 14
at the corresponding circumferential wound portions 14b so as to be
disposed between the claw poles 16b and stator yokes 16a of the
different stator sub-cores 15. Thus, the claw poles 16b of the
stator core 13 protrude toward the rotor 7 through the inside
opening and outside of the stator windings 14. Incidentally, each
of the stator core constituent members 16 constituting the stator
sub-core 15 has a claw pole 16b at one circumferential end but has
not a claw pole 16b at the other circumferential end. Thus, the
coil end portion of the stator winding 14 largely protrudes toward
one circumferential end of the stator core 13 but hardly protrudes
toward the other circumferential end of the stator core 13.
[0035] In the above description, the method is adopted to which the
stator winding 14 is subjected to form winding and then disposed in
the stator sub-core 15. However, for instance, a pair of the stator
sub-cores 15 may be bound by the connecting member and the stator
winding 14 may directly be wound around such stator sub-cores. The
winding used in this case may be a round wire round in
cross-section as well as a rectangular wire rectangular in
cross-section. Further, U-shaped separate coils may be inserted
into the stator-sub cores from one end thereof and joined together
at the other end by welding or caulking, thereby forming a loop
coil.
[0036] A description is next made of the relationship between the
magnetic pole of the rotor 7 and the U-phase stator magnetic pole
6a taking the U-phase as an example with reference to FIG. 3. As
described earlier, the rotor 7 is supported rotatably around the
shaft 8 and configured to include the yoke 10 and permanent magnet
11 provided on the outer circumference of the sliding bearing 9.
The permanent magnet 11 in the present embodiment is magnetized to
have 20 poles; therefore, an angle p1 of one pole is 18 degrees in
mechanical angle. In addition, also the claw pole pitch p2 of the
stator 6 in the present embodiment is 18 degrees in mechanical
angle, which is equal to the magnetic pole pitch of the rotor 7. As
there is a combination of the number of poles and the number of
slots in a motor having windings wound through general concentrated
winding, it is not necessary to make their numbers of pitches equal
to each other. The claw pole pitch P2 of the stator magnetic pole
6a may be larger or smaller than the magnetic pole pitch p1 of the
magnet. The claw pole pitch p2 is made slightly large or small to
reduce a magnetic flux interlinked with the stator winding 14.
However, the high-harmonic component of the magnetic flux
interlinked with the phase winding is reduced, providing an
advantage in terms of reduction in iron loss, sound and vibration.
Thus, the claw pole pitch p2 may be changed as usage. Further, the
claw pole pitch may not be made uniform, that is, the magnetic
poles may be varied in arrangement, thereby reducing cogging
torque.
[0037] Each stator core 13 is secured to the housing main body 2b
and to the partition wall 12 so that a gap g as a magnetic circuit
is a distance between the outer circumferential surface of the
partition wall 12 and the surface of the permanent magnet 11 as
shown in FIG. 3. It is configured that cooling water flows in
between the permanent magnet 11 and the partition wall 12. The
partition wall 12 is configured to prevent the cooling water
leaking to the side of the stator 6.
[0038] The constitution of the first embodiment has been described
thus far. The function and effect of the first embodiment are
described below.
[0039] According to the first embodiment, the rotating electric
machine for driving the pump includes the stator and the rotor. The
stator includes a plurality of stator windings circumferentially
arranged at predetermined intervals and a stator core. The stator
core includes a stator yoke and a plurality of claw poles which
protrude from the stator yoke toward the rotor side through the
inside opening and outside of the stator winding. The stator yoke
is configured to be divided in association with the stator winding.
Thus, a magnetic flux will not leak to the other stator winding
side to improve efficiency. The magnetic flux will hardly come and
go between the stator windings to reduce variations of the magnetic
flux between the phases.
[0040] The stator core of the first embodiment is divided into a
pair of segments each located from the inside opening of the stator
winding to a corresponding one of both the axial sides thereof,
whereby such molded parts can be reduced in size. This can downsize
a manufacturing apparatus and make it easy for the stator winding
to be wound, which enhances productivity. In particular, the stator
core is made of a dust core; therefore, density can be increased,
which can further enhance a characteristic.
[0041] The stator core of the first embodiment is axially divided
at the position of the stator winding; therefore, the stator
winding can extremely easily be wound around the stator core. It
becomes possible that the stator core is first formed into a wound
state and then attached to the stator core. Incidentally, the same
function and effect can be provided as those provided by dividing
the stator core into a pair of segments each located from the
inside opening of the stator winding to a corresponding of the
axial sides thereof.
[0042] The stator core of the first embodiment is axially divided
into the four stator core constituent members at the inside opening
of the stator windings and at the position of the stator winding,
and the stator core constituent members are formed to have the same
shape. Thus, all the stator core constituent members can be molded
by a single mold. In addition to further downsizing the
manufacturing apparatus, the stator winding can further easily be
wound, thereby largely enhancing the productivity. Needless to say,
if the stator core is composed of a dust core, the density can
further be increased.
[0043] The stator core of the first embodiment is composed of a
dust core; therefore, a complicate shape can easily be molded with
a manufacturing mold and the occurrence of the eddy current can be
reduced as much as possible.
[0044] The stator winding of the first embodiment has the one
circumferential end portion protruding from the stator core;
therefore, a cooling effect can be improved by exposing it from the
stator core producing heat. The other circumferential end portion
of the stator winding comes into the stator core; therefore, a
circumferential gap between the stator magnetic poles can be
narrowed to reduce variations in the pitches of the claw poles as
much as possible. As described above, the stator winding is exposed
from the one circumferential end portion of the stator core and the
other circumferential end of the stator winding comes into the
stator core; therefore, both the function and effect, that is,
cooling of the stator winding and the reduction in the variations
of the claw pole pitches, can be provided. In order to provide a
configuration in which the one circumferential end portion of the
stator winding is exposed from the stator core and the other
circumferential end portion of the stator winding comes into the
stator core, it is preferable that the number of the claw poles of
the stator core be even numbers for each magnetically divided
stator sub-core. In this way, a wasteful portion can be reduced as
much as possible.
[0045] The electric motor portion of the first embodiment is such
that the rotor is disposed on the inner circumferential side of the
stator core and drives the pump, the partition wall is disposed
between the claw poles and the rotor, and a discharge medium to be
discharged by the pump is led into the inside of the partition wall
including the rotor. Therefore, it can be prevented that the stator
comes into contact with the discharge medium to rust. In
particular, since the first embodiment uses cooling water as a
discharge medium, not only the rotor can be cooled but also the
rotor side can be cooled through the partition wall.
[0046] The claw poles of the stator core of the first embodiment
are each tapered, which provides the function and effect of
contributing to an improvement in mechanical strength and to an
improvement in coefficient of use of magnetic flux, increasing
output. Further, since the claw pole is skewed, magnetic noise can
be reduced. The opposed claw poles of the stator core constituent
members are brought into contact with each other, which provides
the function and effect of contributing to an improvement in
mechanical strength and to an improvement in coefficient of use of
magnetic flux, increasing output.
[0047] According to the first embodiment, the rotating electric
machine for driving the pump includes the stator and the rotor. The
stator includes a plurality of stator windings circumferentially
arranged at predetermined intervals and a stator core. The stator
core is configured to be provided along the circumferential portion
of the stator winding and to form a plurality of magnetic poles on
the side of the rotor, the stator core being divided on the stator
winding basis. Thus, the stator core is completely divided and the
coil end portion of the stator winding located at a position
between the completely divided stator cores can be exposed to air.
This can enhance cool performance of the stator winding. The stator
core can further be subdivided, which can enhance productivity.
[0048] Since the housing of the first embodiment is made of a
nonmagnetic material, a magnetic flux will not leak to the other
stator magnetic poles through the housing.
[0049] Since the stator magnetic pole of the first embodiment is
secured at its outer and inner circumferences to the partition wall
and to the housing, it serves to reinforce the strength of the
stator core. In particular, if the stator core is formed of a dust
core, it is effective to reinforce the strength of the stator
core.
[0050] The function and effect of the first embodiment has been
described thus far. Other applicable configurations are described
below.
[0051] In the first embodiment, the stator core is
circumferentially divided for each stator winding as means for
magnetically dividing the stator yoke. Since it is needed only to
magnetically divide the stator core, the stator yokes may be
integrally formed of a nonmagnetic member. In this case, it is
necessary to select a material having almost the same linear
expansion coefficient as the stator yoke.
[0052] In the first embodiment, the stator core is axially divided
into a plurality of segments. However, if the stator winding is
directly wound around the stator core, it is not necessary to
axially divide the stator core. If the stator core is not divided
as described above, it becomes difficult to wind the stator winding
around the stator core but it becomes easy for the magnetic flux to
pass through the stator core, leading to improved efficiency.
[0053] While the claw pole is formed to be tapered, that is, to be
almost trapezoidal in the first embodiment, it may be formed to
extend at the same width.
[0054] In the first embodiment, the stator winding is wound so that
only the one circumferential end thereof protrudes from the stator
core. However, in the case of emphasizing cooling, both the
circumferential end of the stator windings may protrude from the
stator core. On the other hand, in the case of emphasizing a
reduction in variations of the claw pole pitches as when the number
of the claw poles is increased, both the circumferential ends of
the stator windings may not protrude from the stator core.
[0055] While the stator core is formed of a dust core in the first
embodiment, since the dust core is fragile, it is preferable to
mold the periphery thereof including the stator winding with a
nonmagnetic insulating member such as resin. In this case, if the
front surface of the inner circumference of the stator core is
molded, such an insulating member can have a function of a
partition wall. Further, the stator core may be formed by punching
a iron plate.
[0056] The rotor of the first embodiment adopts the so-called
surface magnet type in which permanent magnets are provided on the
outer circumference thereof. However, it may adopt the so-called
buried magnet type in which a plurality of permanent magnets are
circumferentially buried inside the rotor.
[0057] If a permanent magnet is used for the rotor, in addition to
a generally used ferrite magnet and neodymium magnet, the permanent
magnet may be used that is obtained by binding neodymium (Nd)
powder with a binder whose precursor has high affinity. Examples of
the precursor having high affinity include e.g. alkoxysiloxane and
alkoxysilane, which are a precursor of SiO.sub.2. The powder of
neodymium (Nd) is formed like a plate, which has a value of X- or
y-axis direction several times greater than that of Z-axis
direction, a height-direction, that is, which is formed thin.
[0058] The greater the X- or Y-axis size of the neodymium (Nd)
powder, the better. For instance, if the powder having an X- or
Y-axis size of 45 .mu.m or more is used, residual performance is
improved. Although it is unavoidable that powder including small
granules is mixed because of cracked powder of neodymium (Nd)
during molding, it is desirable that half or more of the powder has
a size of 45 .mu.m or more. If 70% or more of the powder has a size
of 45 .mu.m or more, more preferable magnet performance can be
provided. If 90% or more of the powder has a sized of 45 .mu.m or
more, furthermore preferable results can be provided. Incidentally,
if neodymium (Nd) further contains slight dysprosium, heat
resistance can be improved. Containing dysprosium can maintain
satisfactory magnetic property even if the rotating electric
machine rises in temperature. A content ratio of dysprosium is
about several percent and 10% or less at a maximum. The magnet
binding the neodymium power with SiO.sub.2 mentioned above is used
to provide an effect of improving magnetic property and heat
resistance.
Second Embodiment
[0059] An electric water pump according to a second embodiment of
the present invention is next described with reference to FIG. 5.
FIG. 5 is a perspective view of an electric motor portion,
separately illustrating its component parts. It is to be noted that
parts common to those of the first embodiment are designated with
like terms and with like reference numerals.
[0060] The second embodiment is different from the first embodiment
in that the partition wall is not provided and instead an end plate
18 serving as a positioning member is provided. In the first
embodiment, the stator magnetic poles 6a, 6b, 6c are secured by the
inner circumference of the housing main body 2b and by the outer
circumference of the partition wall 12. In the second embodiment,
however, because of no partition wall, annular end plates 18 are
each secured to a corresponding one of the key grooves 16a-3
located at both axial ends of the stator core 13 to fix the stator
magnetic poles 6a, 6b, 6c. The end plate 18 is composed of a
nonmagnetic ring-shaped member formed with a planar surface on its
one axial end face and with an annular projection 18a on the other
axial end face. This projection 18a is fitted into the key groove
16a-3. Both the end plates 18 are configured to axially put the
stator core 13 therebetween for support. Incidentally, because of
no partition wall, the present embodiment needs to seal the pump
construct side and electric motor portion side by a seal structure
to prevent cooling water from leaking to the electric motor portion
side or to mold the inner circumference of the stator 6 with resin
or the like.
[0061] Although the shaft and bearing are not illustrated at the
center of the rotor 7, the present embodiment may provide the shaft
8 and bearing 9 similarly to the first embodiment and arrange
reduction gears in the space portion thereof.
[0062] The configuration of the second embodiment has been
described thus far. The function and effect of the second
embodiment are described below.
[0063] According to the second embodiment, the positioning members
for positioning the stator cores divided are each fitted into a
corresponding one of the axial end faces of the stator cores.
Therefore, the stator cores can be positioned at respective
determined positions. In particular, if the positioning members are
made of a nonmagnetic material, the stator cores can magnetically
be divided.
[0064] The stator core of the second embodiment is axially divided
into a plurality of stator core constituent members at least in the
inside opening of the stator winding. The stator core constituent
members have the same shape. The connecting member made of a
magnetic material is fitted to a position which corresponds to the
inside opening of the stator winding and where adjacent stator core
constituent members are opposed to each other. Thus, even if a
space exists, the space being provided to fit the positioning
member to a position not located on the lateral end face of the
stator core, the space can be buried by the connecting member made
of a magnetic material, which prevents degradation in magnetic
property.
Third Embodiment
[0065] A description will be made of a third embodiment of a
product using a rotating electric machine embodying the present
invention taking an alternating-current generator mounted on an
automobile with reference to FIGS. 6 to 9. FIG. 6 is a lateral
cross-sectional view of the vehicle alternating-current generator.
FIG. 7 is a perspective view of a rotor and a generator. FIG. 8 is
a perspective view of the rotor and generator with the stator of
FIG. 7 spaced apart toward the outer circumference and with a fan
attached to the rotor removed. FIG. 9 is an enlarged perspective
view of a W-phase magnetic pole of the stator. It is to be noted
that parts common to those of the other embodiments are designated
with like terms and with like reference numerals.
[0066] The vehicle alternating-current generator 19 of the present
invention shown in FIG. 6 includes a front bracket 20 disposed on
the left side in FIG. 6 and a rear bracket 21 disposed on the right
side in FIG. 6. Each bracket is formed in a bottomed cylinder,
i.e., in a bowl-shape having a housing space therein. The brackets
are each bored with variously shaped holes adapted to pass air
therethrough. The front bracket 20 and rear bracket 21 are formed
integrally with fixing portions 23 which project radially and
outer-circumferentially and are bored with fixation holes 22. These
fixing portions 23 are attached to the vehicle with bolts not
shown.
[0067] A rear cover 24 thinner in thickness than each bracket is
attached to an axial end of the rear bracket 21. Similarly to the
brackets, the rear cover 24 is formed in a bottomed cylinder, i.e.,
in a bowl-shape having a housing space therein. Also the rear cover
24 is bored at the axially external end thereof with a plurality of
holes adapted to pass air therethrough. Further, the rear cover is
attached on its outer circumferential side with a terminal 25
connected to a battery.
[0068] Ball bearings 26a and 26b as bearings are attached to
respective radially almost-central positions of the axially
external end portions included in the front bracket 20 and rear
bracket 21, respectively. The ball bearing 26a attached to the
front bracket 20 has an external diameter than that of the ball
bearing 26b attached to the rear bracket 21.
[0069] A shaft 27 is passed through the respective inner rings of
the ball bearings 26a, 26b so as to be supported rotatably with
respect to the front bracket 20 and rear bracket 21.
[0070] A pulley 28 as a rotation transmitting member is secured to
the shaft 27 at the lateral end of the front bracket 20 with a bolt
so as to be rotated integrally therewith. The rotation of an engine
not shown is transmitted from a crank pulley to this pulley 28 via
a belt as an endless transmission belt. Thus, the shaft 27 is
rotated in proportion to the rotation number of the engine and to a
pulley ratio of the pulley to the crank pulley.
[0071] Two slip rings 29 are attached to the end portion of the
shaft 27 on the side of the rear bracket 21 so as to be rotated
integrally with the shaft 27. Electric power is supplied through
two brushes 30 which are slidably moved while pressed to the
respective slip rings 29.
[0072] A front side rotor member 31F and a rear side rotor member
31R both formed of a magnetic material are separately
serration-joined to the rotation-axially almost-central portion of
the shaft 27 so as to rotate integrally therewith. The front side
and rear side rotor members 31F, 31R are such that their outside
ends are allowed to plastic-flow in annular grooves formed in the
shaft 27 so as to restrict their axial movement with the rotor
members axially opposed to and abutted against each other. The
front side rotor member 31F and the rear side rotor member 31R both
secured to the shaft 27 described above constitute a rotor 31.
[0073] A plate-like fan 32 having a plurality of blades on its
outer circumferential side and serving as ventilation means is
mounted to the rotary-axial end face of the rotor 31 on the side of
the rear cover 24 and is rotated integrally with the rotor 31.
Incidentally, the outmost diameter of the fan 32 is greater than
the outer diameter of the rotor 31 and air on the inner
circumferential side of the fan 32 is allowed to flow to the outer
circumferential side by the centrifugal force resulting from the
rotation.
[0074] The front side rotor member 31F and rear side rotor member
31R include shaft portions 31a located on the inner circumferential
side and claw portions 31b located on the outer circumferential
side and formed in an L-shape in axial cross-section. The axial end
portions of the shaft portions 31a of both the rotor members 31F,
31R are opposed to and abutted against each other to constitute a
Rundel-type core. A field coil 33 is wound around the rotary axis
and between the outer circumference of the shaft portion 31a and
the inner circumference of the claw portion 31b. Both ends of the
field coil 33 extend along the shaft 27 and are each connected with
a corresponding one of the slip rings 29 mentioned above. Thus, a
direct current supplied from the brushes 30 through the slip rings
29 flows in the field coil 33 to magnetize the rotor 31, whereby a
magnetic path is formed in the rotor 31 so as to go around the
filed coil 33. The current supplied to the field coil 33 is
controlled according to the condition of the battery so as to start
electric generation when a generation voltage is higher than the
battery voltage of the vehicle. Specifically, an IC regulator (not
shown) as a voltage control circuit adapted to adjust the
generation voltage is incorporated in a rectification circuit 34
described later disposed in the rear cover 24 to control the
terminal voltage of the terminal 25 at constant voltage at all
times.
[0075] An annular step is formed at a portion where the front
bracket 20 axially faces the rear bracket 21. The stator 6
substantially identical to that of the first embodiment is fixedly
put in the step in such a manner that it is circumferentially
divided into a U-phase magnetic pole 6a, a V-phase magnetic pole 6b
and a W-phase magnetic pole 6c. Incidentally, the arrangement of
the stator magnetic poles 6a, 6b, 6c is the same as that of the
first embodiment. The stator 6 is circumferentially divided and
disposed between the front bracket 20 and the rear bracket 21.
Thus, gaps 35 serving as air passages are formed between the stator
magnetic poles 6a, 6b, 6c so as to allow air streams caused by the
fan 32 to pass therethrough. The claw poles 16b of the stator 6 are
opposed to the claw portion 31b of the rotor 31 with a slight gap
formed therebetween.
[0076] The stator 6 is composed of the stator core 13 and stator
winding 14 similarly to the first embodiment. The stator winding 14
is connected to the rectification circuit 34 attached in the rear
cover 24. Further, the rectification circuit 34 is connected to the
battery through the terminal 25. Incidentally, the rectification
circuit 34 is composed of a plurality of diodes. The three-phase
alternating-current voltage induced in the stator windings 14 of
U-phase, V-phase and W-phase is subjected to full-wave
rectification and converted into direct-current voltage, which is
supplied to the terminal 25.
[0077] The rotor 31 is described in detail with reference to FIG.
8.
[0078] As shown in FIG. 8, the front side rotor member 31F and rear
side rotor member 31R are each provided with a plurality of, e.g.,
ten, claw portions 31b arranged circumferentially and each formed
to extend in an L-shape in cross-section from the axially external
side end of the shaft portion 31a. In short, the twenty claw
portions 31b in total are provided. The claw portions 31b are each
formed to radially extend at almost the same width and then axially
extend therefrom in such a tapered manner that its leading end is
reduced in width. The tapered portion of the claw portion 31b is
largely chamfered at a lateral edge of the anti-rotational
direction. The front side rotor member 31F and rear side rotor
member 31R thus formed are secured to the shaft 27 in such a manner
that the field coil 33 is disposed therebetween and the claw
portions 31b are arranged circumferentially alternately with the
ends of the shaft portions 31a abutted against each other.
[0079] The fan 32 as shown in FIG. 7 is mounted to the axially
external end of the rear side rotor member 31R by welding or the
like. This fan 32 is a centrifugal fan in which one circumferential
side of a projecting portion of a metal plate circumferentially
formed with a plurality of projections is bent almost arcuately and
almost vertically by a press machine to integrally form blades each
having a slant surface slant with respect to the radial direction.
Thus, when the fan 32 is rotated clockwise in FIG. 7 to allow air
to flow in a direction designated with an arrow, that is, from the
inner circumferential side to the outer circumferential side.
[0080] The stator 6 is next described in detail with reference to
FIG. 9.
[0081] The stator 6 of the present embodiment is almost identical
to that of the first embodiment as described earlier. However, the
number of the claw poles is five, the odd number, for each stator
sub-core 5 as shown in FIG. 9. Along with this, the coil end
portions 14a of a stator winding 14 protrude from both the
circumferential ends of a stator core 13.
[0082] The stator cores 13 are each composed of four stator core
constituent members 16. The number of claw poles 16b opposed to
each other in each stator sub-core 15 is two, the even number, and
the number of claw poles 16b on the axially external side is three,
the odd number. Thus, two kinds of the stator core constituent
members 16 are required. Of the two, the stator core constituent
member 16 having the three claw poles 16b are configured so as to
be arranged at both circumferential ends and at a circumferentially
almost-central portion. The stator core constituent member 16
having the two claw poles 16b is configured such that two claw
poles 16b are evenly arranged with a space for a single claw pole
16b made at each of both the circumferential ends. The stator core
constituent members 16 of the two kinds constructed as above are
axially assembled with each other so as to alternately arrange
their claw poles 16b, thus, forming the stator sub-core 15.
Further, the two stator sub-cores 15 are axially assembled with
each other so as to be symmetrical, thereby forming the stator core
13. Since the stator core 13 has the claw poles 16b at both the
circumferential ends, the coil end portions 14a of the stator
winding 14 respectively protrude from both the circumferential ends
of the stator core 13.
[0083] The operation of the present embodiment is next
described.
[0084] Along with the start of the engine, rotation is transmitted
from the crankshaft through the belt to the pulley 28, thus
rotating the rotor 31 via the shaft 27. At this moment, direct
current is supplied from the brushes 30 through the slip rings 29
to the field coil 33 provided on the rotor 31 to generate a
magnetic flux circulating the inner and outer circumferences of the
field coil 33. This alternately forms N-poles and S-poles on the
claw portions 31b of the rotor 31. The magnetic flux of the field
coil 33 passes from the N-pole claw portion 31b of the front side
rotor member 31F through one side claw magnetic pole 16b of the
stator core 13, circulating around the stator winding 14, and reach
the other side claw pole 16b. Further, the magnetic flux reaches
the S-pole claw portion 31b of the rear side rotor member 31R. In
this way, a magnetic circuit circulating the rotor 31 and the
stator 6 is formed. Such a magnetic circuit is generated for each
phase, thereby generating three-phase alternating-current induced
voltage in the stator winding 14.
[0085] The alternating current voltage thus generated is subjected
to full-wave rectification by the rectification circuit 34 to be
converted into direct-current voltage. The direct-current voltage
thus rectified is sent to the terminal 25 connected to the battery.
The magnitude of the induced voltage varies in conjunction with
field current and with the number of rotation. In order to make the
voltage of the battery connected to the terminal constant, it is
necessary therefore to control current applied to the field coil 33
in response to the number of rotation. The control of current
applied to the field coil 33 is exercised by an IC regulator (not
shown) incorporated in the rectification circuit 34.
[0086] When the rotor 31 rotates, the fan 32 rotates together with
the rotor 31. The fan 32 is mounted on the rotor 31 only on the
side of the rear cover 24. Thus, as designated with dashed arrows
in FIG. 6, outside air enters the holes bored in the front bracket
20, passing through the air passages 35 defined between the stator
magnetic poles 6a, 6b, 6c, and flows out of the holes bored in the
rear bracket 21 on its radial outside. In addition, outside air
enters the holes bored in the axial ends of the rear bracket 21 and
rear cover 24, merging with the air flowing in from the side of the
front bracket 20, and flows out from the holes bored in the rear
bracket 21 on the radial outside. In this way, the stator 6, rotor
31 and rectification circuit 34 are cooled. In particular, the
stator windings 14 projecting from both the circumferential sides
of the air passages 35 are cooled by the air passing through the
air passages 35. Consequently, the stator 6 can sufficiently be
cooled.
[0087] The configuration of the third embodiment has been described
thus far. The function and effect of the third embodiment are
described below.
[0088] According to the third embodiment, the alternating-current
generator includes the stator and the rotor. The stator includes a
plurality of stator windings arranged at predetermined intervals
and a stator core. The stator core includes a stator yoke and a
plurality of claw poles which protrude from the stator yoke toward
the rotor side through the inside opening and outside of the stator
winding. The stator yoke is magnetically divided in association
with the stator winding. The magnetic flux generated by the rotor
passes through the claw poles to be interlinked with the stator
winding. The magnetic flux interlinked with the stator winding
varies based on the rotation of the rotor to induce voltage in the
stator winding. Thus, the magnetic flux will not leak to the other
stator winding side to improve generating efficiency. Further, the
magnetic flux will hardly come and go between the stator windings
to reduce variations of the magnetic flux between the phases. Since
each phase is configured as an independent magnetic circuit, even
if the axial thickness is increased, a balance between the magnetic
flux interlinked with each phase and the inductance of the winding
is satisfactory.
[0089] The alternating-current generator of the third embodiment is
provided with the air passages adapted to axially pass air
therethrough between the stator windings thereof and with the
ventilation means for allowing air to flow through the air
passages. Thus, the effect of cooling the stators can be improved.
In particular, if the odd number of claw poles is provided for each
magnetically divided stator yoke, then the coil end portions of the
stator winding will protrude from both the circumferential ends of
the stator core. The effect of cooling the stator winding can
further be improved.
[0090] According to the alternating-current generator of the third
embodiment, the rotor is disposed on the inner circumferential side
of the stator cores and the ventilation means is composed of a fan
provided at least on one axial end side of the rotor and having the
outer diameter greater than that of the rotor. Thus, the amount of
ventilation air can be increased, which can improve the cooling
effect. Incidentally, since the stator of the present embodiment is
divided into segments in the circumferential direction, it is
possible to assemble the stator magnetic poles to the rotor from
the outer circumferential side. Thus, although the outer diameter
of the fan is greater than that of the rotor, the fan can be
assembled.
[0091] The fan attached to the rotor of the alternating-current
according to the third embodiment is attached only to the end face
thereof on the side where the rectification circuit is disposed.
Although the fan is single, air can be allowed to flow from both
the axial ends of the rotor to the outer circumferential side
thereof. Thus, even the single fan can sufficiently cool the
rectification circuit and the stator.
[0092] The stator of the alternating-current generator according to
the third embodiment is such that the stator core is divided into
segments for each stator winding; therefore, component replacement
is enabled for each phase. This provides the function and effect
that even if a failure occurs, the minimum component replacement
enables maintenance.
[0093] The function and effect of the third embodiment has been
described thus far. Other applicable configurations are described
below.
[0094] The stator winding is designed to protrude from both the
circumferential ends of the stator core in the third embodiment.
However, similarly to the first embodiment, the stator winding
protrudes only from the one circumferential end side of the stator
core, which provides the cooling effect. In this case, since the
circumferential gap between the adjacent stator magnetic poles can
be reduced, variations in the pitches of the claw poles can be
reduced as much as possible.
[0095] The stator core is divided into segments for each stator
winding in the third embodiment. However, their stator yokes may
integrally be made of a nonmagnetic member and an air passage may
be formed in the nonmagnetic member. In this way, each stator core
can circumferentially be positioned with ease. Incidentally,
exposition of the stator winding to the inside of the air passage
can improve the cooling effect.
[0096] The third embodiment is described through the three-phase
three-pole stator. In order to reduce an influence on the
eccentricity of the rotor, the stator may be configured so as to be
of a three-phase six-pole, and to be arranged at intervals of about
60 degrees in mechanical angle and at a phase difference of
three-phase. In this case, the efficiency on the eccentricity can
be reduced by arranging the same-phase coils on the diagonal
line.
Fourth Embodiment
[0097] A fourth embodiment is described in which the stator of the
vehicle alternating-current generator is modified, with reference
to FIG. 10. FIG. 10 is a perspective view of a stator and a rotor.
It is to be noted that parts common to those of the other
embodiments are designated with like terms and with like reference
numerals.
[0098] A stator 6 of the fourth embodiment is such that two stator
windings 14 are wound for each phase. In other words, the stator
winding 14 is wound for each stator sub-core 15. Thus, the stator
winding 14 goes around the outside of the one axial end of the
stator core 13. A pair of the stator sub-cores 15 thus constructed
are fixedly abutted against and opposed to each other so as to be
paired at the axial end portion where the stator winding 14 is not
wound. Thus, the stator 6 is configured such that the stator
windings 14 protrude from both the axial ends of the stator core
13. Incidentally, the two stator windings 14 wound around the same
phase is connected in series with each other.
[0099] Since the stator windings 14 are exposed to both the axial
ends of the stator cores 13 as described above, the effect of
cooling the stator windings 14 can be improved. Further, if a fan
is arranged in the inner circumferences of the protruding portions
of the stator windings 14, the further cooling effect can be
expected. In this case, if the fans are mounted to both the axial
ends of the rotor 7, both the stator windings can be cooled.
Fifth Embodiment
[0100] A fifth embodiment is described in which the stator of the
vehicle alternating-current generator is further modified, with
reference to FIGS. 11A and 11B. FIG. 11A is a perspective view of a
stator and a rotor, and FIG. 11B is a perspective view illustrating
only a V-phase magnetic pole and a W-phase magnetic pole. It is to
be noted that parts common to those of the other embodiments are
designated with like terms and with like reference numerals.
[0101] A stator 6 of the fifth embodiment is similar to the stator
6 of the fourth embodiment. However, the stator 6 of the fifth
embodiment is different from that of the fourth embodiment in that
six stator windings 14 are made independent of each other and one
axial end side three-phase windings and the other axial end side
three-phase windings have a phase-difference of 30 degrees in
electric angle between the same phase coils. In other words, a pair
of stator sub-cores 15 are arranged to be offset from each other by
an electric angle of 30 degrees. This can provide a six-phase
stator 6.
[0102] The six-phase stator 6 thus configured can produce the
function and effect that full-wave rectification provides
direct-current voltage with a low voltage-ripple.
[0103] The inventions comprehendable from the embodiments described
above and other than the inventions recited in the following claims
are described below together with their function and effect.
[0104] (1) A vehicle alternating-current generator comprising:
[0105] a stator including: [0106] a stator core having a plurality
of circumferentially arranged magnetic pole portions; and [0107] a
plurality of stator windings each wound at a predetermined
circumferential angle; [0108] wherein an air passage located
between the stator core windings and adapted to enable air to flow
at least one of coil end portions; and
[0109] a rotor provided rotatably with respect to the stator and
having a plurality of magnetic poles opposed to the magnetic pole
portions of the stator core.
[0110] With such a configuration, the function and effect almost
similarly to those of claim 17 can be provided. However, the main
object of this invention is to cool the stator winding; therefor,
it is not needed to magnetically divide the stator core.
[0111] (2) The vehicle alternating-current generator recited in
item (1), wherein a fan is provided only on one axial end side of
the rotor so as to allow air to flow the air passage, and a
rectification circuit is provided to rectify voltage induced in the
stator winding, and the generator includes a path adapted to allow
air, caused by rotation of the fan, to flow via the rectification
circuit and toward the outer circumferential side of the fan and
another fan adapted to allow air to flow from the other axial end
side where the fan is not provided in the rotor through the air
passage to the outer circumferential side of the fan.
[0112] With such a configuration, even the single fan can cool the
rectification circuit, the stator and the rotor.
[0113] (3) The vehicle alternating-current generator recited in
item (1), wherein a fan is provided only on one axial end side of
the rotor so as to allow air to flow the air passage, the stator
winding is wound to be exposed from the stator core on the axial
end side of the stator core, the fan is formed to have a diameter
smaller than the inner diameter of the stator winding exposed to
the axial end side of the stator core and to dispose in the inner
circumference of the stator winding, and the stator winding exposed
to the axial end side of the stator core is wound to increase its
diameter toward the axial end face. With such a configuration,
resistance of air flowing from the fan toward the outer
circumferential side can be suppressed. Thus, an air flow rate is
increased to improve an cooling effect and air resistance applied
to the rotor can be reduced.
* * * * *